Semiconductor device assemblies including multiple stacks of different semiconductor dies

ABSTRACT

A semiconductor device assembly is provided. The assembly comprises a package substrate, a first stack of semiconductor dies having a first set of planform dimensions disposed over a first location on the substrate, a second stack of semiconductor dies having a second set of planform dimensions different from the first set disposed over a second location on the substrate, and an encapsulant at least partially encapsulating the substrate, the first stack and the second stack. The first stack of semiconductor dies has a first planform area, the second stack of semiconductor dies has a second planform area, and a sum of the first and second planform areas can be at least 50%, 67%, 75%, or even more of an area of the package substrate.

TECHNICAL FIELD

The present disclosure generally relates to semiconductor devices, andmore particularly relates to semiconductor device assemblies includingmultiple stacks of different semiconductor dies.

BACKGROUND

Packaged semiconductor dies, including memory chips, microprocessorchips, and imager chips, typically include one or more semiconductordies mounted on a substrate and encased in a plastic protective coveringor covered by a heat-conducting lid. The die can include active circuits(e.g., providing functional features such as memory cells, processorcircuits, and/or imager devices) and/or passive features (e.g.,capacitors, resistors, etc.) as well as bond pads electrically connectedto the circuits. The bond pads can be electrically connected toterminals outside the protective covering to allow the die to beconnected to higher level circuitry.

To provide additional functionality, additional semiconductor dies canbe added to a semiconductor device assembly. One approach to includingadditional semiconductor dies involves stacking the dies over thesubstrate. To facilitate the electrical connection of dies to thesubstrate, the dies can be arranged in a shingled stack, where each dieis offset horizontally from a die below to leave exposed contact pads ofthe die that can be bonded (e.g., with a wirebond) to a correspondingbondfinger on the substrate. In this regard, FIG. 1 illustrates asemiconductor device assembly 100 in which a shingled stack 102 of dies103 connected by adhesive layers are stacked on a substrate 101 andelectrically connected to bondfingers 105 on the substrate 101 bywirebonds 106. The stack 102, substrate 101 and wirebonds 106 areencapsulated by, e.g., a mold material 105.

Semiconductor device assemblies are frequently provided in one of anumber of widely-adopted physical formats for use in electronic devices.These formats may specify, e.g., the overall dimensions of theassemblies (i.e., width, length and height), the connectivity mechanisms(e.g., solder ball arrays, pads, pin outs, etc.), and other features ofthe assemblies. When a semiconductor die, or a stack thereof, have aplanform area that utilizes most of the available space on a substratethat is required for a given format, as in FIG. 2, there is littlewasted space in the package. As can be seen with reference to FIG. 2, astack 202 of semiconductor dies 203 with a planform area that covers amajority (e.g., more than half, more than two-thirds, more thanthree-fourths, etc.) of the area of the substrate 201 leaves littlewasted space in the assembly 200. As semiconductor dies continue toshrink due to process and technological advances, however, smaller diesmay not make good use of the area available for a given assembly format.

For example, FIG. 3 illustrates a semiconductor device assembly in whicha stack 302 of semiconductor dies 303 with a planform area that coversless than a majority (e.g., less than half, less than two-thirds, lessthan three-fourths, etc.) of the area of the substrate 301 leaves agreat deal of wasted space in the assembly 300. To address thisinefficiency, one approach involves using multiple stacks of smallersemiconductor dies, as shown in FIG. 4, but this approach can also beinefficient when the required format of a device assembly is notefficiently used even by multiple stacks of smaller semiconductor dies.As can be seen with reference to the semiconductor device assembly 400illustrated in FIG. 4, even two stacks 402 and 412 of smallersemiconductor dies 403 may cover less than a majority (e.g., less thanhalf, less than two-thirds, less than three-fourths, etc.) of the areaof a substrate 401 for a given assembly format, leaving a great deal ofwasted space in the assembly 400.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a semiconductor device assembly including a stack ofsemiconductor dies.

FIG. 2 illustrates a semiconductor device assembly including a stack ofsemiconductor dies.

FIG. 3 illustrates a semiconductor device assembly including a stack ofsemiconductor dies.

FIG. 4 illustrates a semiconductor device assembly including multiplestacks of semiconductor dies.

FIG. 5 illustrates a semiconductor device assembly including multiplestacks of different semiconductor dies in accordance with an embodimentof the present technology.

FIG. 6 illustrates a semiconductor device assembly including multiplestacks of different semiconductor dies in accordance with an embodimentof the present technology.

FIG. 7 illustrates a semiconductor device assembly including multiplestacks of different semiconductor dies in accordance with an embodimentof the present technology.

FIG. 8 is a flow chart illustrating a method of making a semiconductordevice assembly in accordance with one embodiment of the presenttechnology.

FIG. 9 is a schematic view showing a system that includes asemiconductor device assembly configured in accordance with anembodiment of the present technology.

DETAILED DESCRIPTION

In the following description, numerous specific details are discussed toprovide a thorough and enabling description for embodiments of thepresent technology. One skilled in the relevant art, however, willrecognize that the disclosure can be practiced without one or more ofthe specific details. In other instances, well-known structures oroperations often associated with semiconductor devices are not shown, orare not described in detail, to avoid obscuring other aspects of thetechnology. In general, it should be understood that various otherdevices, systems, and methods in addition to those specific embodimentsdisclosed herein may be within the scope of the present technology.

As discussed above, semiconductor device assemblies, such assemiconductor memory packages, may be provided in a number of differentphysical formats with predetermined sizes. When a semiconductor die isnot sized to efficiently utilize the available space in a particularphysical format, the inefficiency of unused space in the package canincrease the relative cost of the assembly (e.g., as compared to anassembly in which a shorter stack of larger dies can provide the samememory capacity, or an equivalent stack of larger dies can providegreater memory capacity). Accordingly, it is desirable to provide moreefficient use of available space in semiconductor device assemblies.

In this regard, several embodiments of the present technology aredirected to semiconductor device assemblies that include a packagesubstrate, a first stack of semiconductor dies having a first set ofplanform dimensions disposed over a first location on the substrate, asecond stack of semiconductor dies having a second set of planformdimensions different from the first set disposed over a second locationon the substrate, and an encapsulant at least partially encapsulatingthe substrate, the first stack and the second stack. The first stack ofsemiconductor dies has a first planform area, the second stack ofsemiconductor dies has a second planform area, and a sum of the firstand second planform areas can be at least 50%, 67%, 75%, 90%, or evenmore of an area of the package substrate.

Specific details of several embodiments of semiconductor devices aredescribed below. The term “semiconductor device” generally refers to asolid-state device that includes a semiconductor material. Asemiconductor device can include, for example, a semiconductorsubstrate, wafer, or die that is singulated from a wafer or substrate.Throughout the disclosure, semiconductor devices are generally describedin the context of semiconductor dies; however, semiconductor devices arenot limited to semiconductor dies.

The term “semiconductor device package” can refer to an arrangement withone or more semiconductor devices incorporated into a common package. Asemiconductor package can include a housing or casing that partially orcompletely encapsulates at least one semiconductor device. Asemiconductor device package can also include an interposer substratethat carries one or more semiconductor devices and is attached to orotherwise incorporated into the casing. The term “semiconductor deviceassembly” can refer to an assembly of one or more semiconductor devices,semiconductor device packages, and/or substrates (e.g., interposer,support, or other suitable substrates). The semiconductor deviceassembly can be manufactured, for example, in discrete package form,strip or matrix form, and/or wafer panel form. As used herein, the terms“vertical,” “lateral,” “upper,” and “lower” can refer to relativedirections or positions of features in the semiconductor device ordevice assembly in view of the orientation shown in the Figures. Forexample, “upper” or “uppermost” can refer to a feature positioned closerto or closest to, respectively, the top of a page than another featureor portion of the same feature. These terms, however, should beconstrued broadly to include semiconductor devices having otherorientations, such as inverted or inclined orientations wheretop/bottom, over/under, above/below, up/down, and left/right can beinterchanged depending on the orientation.

FIG. 5 is a simplified cross-sectional view of a semiconductor deviceassembly including multiple stacks of different semiconductor dies inaccordance with an embodiment of the present technology. Thesemiconductor device assembly 500 includes a substrate 501, a firststack 502 of first semiconductor dies 503 and a second stack 512 ofsecond semiconductor dies 513, which have a different set of planformdimensions (e.g., length and/or width) than the first semiconductor dies503. In this regard, the first semiconductor dies 503 of the first stack502 have a first length L₁ and a first width W₁, and the secondsemiconductor dies 513 of the second stack 512 have a second length L₂and a second width W₂, where L₁≠L₂, and/or W₁≠W₂. By utilizing stacks ofsemiconductor dies with different sets of planform dimensions, theavailable space in a device assembly format of a predetermined size canbe more efficiently exploited than with a single stack of semiconductordies or with multiple stacks of semiconductor dies with the samedimensions. In this regard, the first stack 502 has a first area A₁, thesecond stack 512 has a second area A₂, and a sum of the first and secondareas can be at least 50%, 67%, 75%, 90%, or even more of an area of thesubstrate 501.

In accordance with one aspect of the present technology, thesemiconductor dies 503 and 513 of the first and second stacks 502 and512 can be memory dies (e.g., NAND flash, NOR flash, DRAM, PCM, FeRAM,MRAM, etc.) and device assembly 500 can be a packaged memory device. Thesemiconductor dies 503 and 513 can be the same kind of memory (e.g.,both NAND flash, both NOR flash, both DRAM, etc.) to provide increasedmemory capacity in device assembly 500 when compared to a deviceassembly with less-efficiently utilized physical space (e.g., due to theuse of a single stack, or multiple stacks of the same dimensions).

Although in the foregoing example embodiment, a semiconductor deviceassembly with two stacks of eight semiconductor dies has beenillustrated, in other embodiments, the number of semiconductor dies in astack, and the number of stacks in a device assembly, may vary. Forexample, FIG. 6 is a simplified plan view of a semiconductor deviceassembly including three stacks of two different semiconductor dies(e.g., semiconductor dies with two different sets of planformdimensions) in accordance with an embodiment of the present technology.As can be seen with reference to FIG. 6, the semiconductor deviceassembly 600 includes a substrate 601 and three stacks 602-604 ofsemiconductor dies, with features similar to those discussed in moredetail above with reference to FIG. 5. Each of the stacks 602-604 isdisposed in a different location on the substrate 601 (e.g., inadjacent, non-overlapping locations). The first stack 602 is a stack ofeight of a first type of semiconductor die with a first set of planformdimensions, and the second and third stacks 603 and 604 are stacks offour of a second type of semiconductor die with a second set of planformdimensions, different from the first. By utilizing stacks ofsemiconductor dies with different sets of planform dimensions, theavailable space in a device assembly format of a predetermined size canbe more efficiently exploited than with a single stack of semiconductordies or with multiple stacks of semiconductor dies with the samedimensions. In this regard, the first stack 602 has a first area, thesecond stack 603 has a second area, the third stack 604 has a thirdarea, and a sum of the first, second and third areas can be at least50%, 67%, 75%, 90%, or even more of an area of the substrate 601.

Moreover, although in the foregoing example embodiments, semiconductordevice assemblies with two different types of semiconductor dies (e.g.,semiconductor dies with two different sets of planform dimensions) havebeen illustrated, in other embodiments a semiconductor device assemblymay have three, four, or even more different types of semiconductordies. In this regard, FIG. 7 is a simplified plan view of asemiconductor device assembly including three stacks of three differentsemiconductor dies (e.g., semiconductor dies with three different setsof planform dimensions) in accordance with an embodiment of the presenttechnology. As can be seen with reference to FIG. 7, the semiconductordevice assembly 700 includes a substrate 701 and three stacks 702-704 ofsemiconductor dies, with features similar to those discussed in moredetail above with reference to FIGS. 5 and 6. Each of the stacks 702-704is disposed in a different location on the substrate 701 (e.g., inadjacent, non-overlapping locations). The first stack 702 is a stack ofeight of a first type of semiconductor die with a first set of planformdimensions, the second stack 703 is a stack of four of a second type ofsemiconductor die with a second set of planform dimensions, differentfrom the first, and the third stack 704 is a stack of four of a thirdtype of semiconductor die with a third set of planform dimensions,different from the first and second. By utilizing stacks ofsemiconductor dies with different sets of planform dimensions, theavailable space in a device assembly format of a predetermined size canbe more efficiently exploited than with a single stack of semiconductordies or with multiple stacks of semiconductor dies with the samedimensions. In this regard, the first stack 702 has a first area, thesecond stack 703 has a second area, the third stack 704 has a thirdarea, and a sum of the first, second and third areas can be at least50%, 67%, 75%, 90%, or even more of an area of the substrate 701.

Although in the foregoing examples, semiconductor device assemblies havebeen illustrated and described as including shingled stacks ofsemiconductor dies, in other embodiments of the present technology,semiconductor device assemblies can include multiple stacks ofsemiconductor dies utilizing different topologies (e.g., verticalstacks, partially shingled stacks, etc.) and interconnectiontechnologies (e.g., TSVs, optical interconnections, inductiveinterconnections, etc.).

According to one aspect of the subject technology, an advantage ofincluding two or more stacks of different semiconductor dies (e.g.,semiconductor dies with different sets of planform dimensions) in asemiconductor device assembly is the additional flexibility provided inlayout of the assembly, which can permit efficient use of the availablespace for a given device assembly format (e.g., providing a greaterdensity of bits for a memory device assembly). In accordance with oneaspect of the subject technology, another advantage of providingmultiple stacks of different semiconductor dies in a semiconductordevice assembly is the reduction in package height that can be achieved(e.g., by using multiple stacks of fewer dies instead of a single,taller stack of dies). Yet another advantage can include the use ofthicker semiconductor dies (e.g., which can be more easily manufacturedthan thinner dies) while maintaining a similar package height as asemiconductor device assembly using a single stack with a greater numberof thinner dies.

FIG. 8 is a flow chart illustrating a method of making a semiconductordevice assembly. The method includes providing a substrate (box 810),stacking a first plurality of semiconductor dies with a first set ofplanform dimensions on the substrate in a first stack (box 820) andstacking a second plurality of semiconductor dies with a second set ofplanform dimensions, different from the first set on the substrate in asecond stack (box 830). In this regard, the first plurality ofsemiconductor dies can be stacked directly over a first location on thesubstrate, and the second plurality of semiconductor dies can be stackeddirectly over a second location on the substrate. The method can furtherincludes wirebonding or otherwise connecting the first and secondpluralities of semiconductor dies to the substrate and providing anencapsulant to at least partially encapsulate the substrate, the firststack and the second stack (box 840).

Any one of the semiconductor device assemblies described above withreference to FIGS. 5-8 can be incorporated into any of a myriad oflarger and/or more complex systems, a representative example of which issystem 900 shown schematically in FIG. 9. The system 900 can include asemiconductor device assembly 902, a power source 904, a driver 906, aprocessor 908, and/or other subsystems or components 910. Thesemiconductor device assembly 902 can include features generally similarto those of the semiconductor devices described above with reference toFIGS. 5-8. The resulting system 900 can perform any of a wide variety offunctions, such as memory storage, data processing, and/or othersuitable functions. Accordingly, representative systems 900 can include,without limitation, hand-held devices (e.g., mobile phones, tablets,digital readers, and digital audio players), computers, vehicles,appliances and other products. Components of the system 900 may behoused in a single unit or distributed over multiple, interconnectedunits (e.g., through a communications network). The components of thesystem 900 can also include remote devices and any of a wide variety ofcomputer readable media.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thescope of the invention. Accordingly, the invention is not limited exceptas by the appended claims.

What is claimed is:
 1. A semiconductor device assembly, comprising: apackage substrate having an upper surface with an upper surface area; afirst stack of semiconductor dies disposed over a first region on thesubstrate, each semiconductor die of the first stack of semiconductordies having a same first length and a same first width; a second stackof semiconductor dies disposed over a second region on the substrate,each semiconductor die of the second stack of semiconductor dies havinga same second length and a same second width; and an encapsulant atleast partially encapsulating the substrate, the first stack and thesecond stack, wherein the first length is different than the secondlength and the second width, and wherein the first region has a firstarea, the second region has a second area, and a sum of the first andsecond areas is at least 90% of the upper surface area of the uppersurface of the package substrate.
 2. The semiconductor device assemblyof claim 1, wherein the first width is different than the second lengthand the second width.
 3. The semiconductor device assembly of claim 1,wherein the first stack of semiconductor dies is connected to thepackage substrate by a first plurality of wirebonds and the second stackof semiconductor dies is connected to the package substrate by a secondplurality of wirebonds.
 4. The semiconductor device assembly of claim 1,wherein the first stack of semiconductor dies includes through substratevias.
 5. The semiconductor device assembly of claim 4, wherein thesecond stack of semiconductor dies includes through substrate vias. 6.The semiconductor device assembly of claim 1, wherein the first stack ofsemiconductor dies comprises a first plurality of memory dies, andwherein the second stack of semiconductor dies comprises a secondplurality of memory dies.
 7. The semiconductor device assembly of claim6, wherein the first plurality of memory dies and the second pluralityof memory dies comprise a single memory type.
 8. The semiconductordevice assembly of claim 7, wherein the single memory type is one ofNAND flash, NOR flash, DRAM, PCM, FeRAM, or MRAM.
 9. The semiconductordevice assembly of claim 1, wherein the package substrate includes aplurality of external connectors operably connected to the first andsecond stacks of semiconductor dies.
 10. A method of making a memorydevice, comprising: providing a substrate having an upper surface withan upper surface area; stacking a first plurality of semiconductor diesover a first region of the substrate in a first stack, each of the firstplurality of semiconductor dies having a same first length and a samefirst width; stacking a second plurality of semiconductor dies differentfrom the first set over a second region of the substrate in a secondstack, each of the second plurality of semiconductor dies having a samesecond length and a same second width; and providing an encapsulant toat least partially encapsulate the substrate, the first stack and thesecond stack, wherein the first length is different than the secondlength and the second width, and wherein the first region has a firstarea, the second region has a second planform area, and a sum of thefirst and second areas is at least 90% of the upper surface area of theupper surface of the package substrate.
 11. The method of claim 10,wherein the first width is different than the second length and thesecond width.
 12. The method of claim 10, wherein the first stack ofsemiconductor dies comprises a first plurality of memory dies, andwherein the second stack of semiconductor dies comprises a secondplurality of memory dies.
 13. The method of claim 12, wherein the firstplurality of memory dies and the second plurality of memory diescomprise a single memory type.